After summarizing famous Object-Oriented methods, some design patterns and design principles that are used to analyze the design software are introduced. The dissertation illustrates that the process of software development, to a great extent, is the process of decomposing. Decomposing can not only degrade the difficulty of software development, but also make the design result to be changeable and maintainable. The dissertation proposes three decomposing-based model principles: self-contained principle, orthogonal principle, and definitude principle. Self-contained principle indicates that there must be nothing omitted after decomposing. Orthogonal principle advises that the common features of more than one entity should be abstracted as a new subsystem so as to be reuse if there are some. Definitude principle proposes that the subsystems decomposed from a domain should be definitive and significative in that domain. In the dissertation, the detailed application guidelines for the principles are provided to help developer to apply them. In the case study of the dissertation, the three principles and Object-Process Diagram are used to model HyperPublisher, a hypermedia authoring tool based on GBH (Graphics-Based Hypermedia system), a research achievement. To satisfy the user requirements and compete with other multimedia authoring tools, the dissertation analyzes the other authoring tools in detail. Finally, a simpler and more flexible HyperPublisher model is proposed based on the essential features of the multimedia authoring domain.